When manufacturing an electronic device, various processes are performed with respect to a workpiece such as a semiconductor substrate. Examples of such a process may include a process performed under a depressurized environment, for example, a film forming process, an etching process or the like.
In processing a workpiece under a depressurized environment, a processing apparatus provided with a process chamber having a depressurizable inner space is used. Typically, such a processing apparatus is further provided with a stage and a plurality of lift pins. The stage is to support a workpiece mounted thereon and has a plurality of through-holes formed therein. The lift pins are configured to be inserted into the plurality of through-holes, respectively. In the processing apparatus, the workpiece is loaded into the process chamber by a transfer device such as a transfer robot. The workpiece loaded into the process chamber is transferred from the transfer device onto upper ends of the plurality of lift pins which protrude from an upper surface of the stage. Thereafter, the workpiece is transferred from the plurality of lift pins onto the stage. Subsequently, the workpiece is subjected to a process.
In such a processing apparatus, relative positions between the upper ends of the plurality of lift pins and the upper surface of the stage are set with a vertical movement of the stage. In the processing apparatus, the stage is configured to be vertically movable. The stage has a plurality of through-holes formed therein. The plurality of lift pins is partially inserted into the plurality of through-holes, respectively, and is supported by the stage. Under the plurality of lift pins, a plurality of pin bearings supported respectively by a plurality of springs, is installed.
In the processing apparatus, the stage is moved downward such that lower ends of the plurality of lift pins are brought into contact with the plurality of pin bearings, respectively. Thus, the upper ends of the plurality of lift pins are located above the upper surface of the stage. Thereafter, a workpiece is transferred onto the upper ends of the plurality of lift pins. Subsequently, the stage is moved upward such that the plurality of lift pins is moved below the upper surface of the stage. In this way, the workpiece is mounted on the stage.
In the conventional processing apparatus, when the plurality of lift pins moves relative to the stage, the plurality of lift pins slides along a wall surface of the stage, Which defines the plurality of through-holes. As such, particles are likely to be generated from at least one of the stage and the lift pins. Such particles may also be generated from the springs. In addition, for the movement of the plurality of lift pins with respect to the stage, clearance (gaps) is required between the plurality of lift pins and the wall surface of the stage defining the plurality of through-holes, respectively. Thus, when the plurality of lift pins move relative to the stage, the plurality of lift pins is likely to clatter. This deteriorates accuracy of transferring the workpiece onto the stage.